In order to achieve stability in the path between launcher and target, stabilization of a projectile can be realized by, preferably, rotation stabilization and/or fin stabilization. For a fin-stabilized barrel-launched projectile, fin deployment must take place after the projectile has left the barrel, since the fins cannot be deployed in the barrel. In order to achieve good manoeuvrability, modern projectiles for artillery purposes often have guide fins or so-called canard fins arranged for guidance of the projectile, which projectiles can at the same time have a finned and rotating tail section or base in order to acquire advantages associated with fin stabilization. Projectiles of this type consequently consist of a fin-stabilizing tail section and a roll-stable front part, the shell body, with guide fins. For such projectiles, the tail section and the shell body are freely movable with respect to each other and the shell body preferably assumes a rotationless state in order to extend deployable guide fins or canard fins which guide the shell. From a communications viewpoint, a non-rotating shell body is suitable for visual or radio communication, for example, since the sensor or antenna on the shell body essentially assumes a rotationless state. Irrespective of the type of projectile, the fin deployment method, as well as the fin deployment mechanism, is of great importance.
Previously known inventions include, for example, U.S. Pat. No. 7,226,016 B2, which describes a method and a device for pressurizing a pressure chamber in the shell body with gas pressure created by the propelling charge during the launch process. The pressure which is created in the pressure chamber is sufficient to displace an external element on the shell body, such as, for example, a protective cap for the fins.
An example of another previously known invention is U.S. Pat. No. 7,083,141 B2, which describes a projectile having radially deployable fins using an accompanying pressurized gas cartridge, which is also used to propel the projectile.